The present invention relates to a method for forming a cross-linked chemical composition and a product of the method as well as apparatus for carrying out the method. More particularly, the invention relates to such a method, apparatus and resulting product wherein numerous variations are possible in characteristics of the resulting product.
Methods have been disclosed in the prior art for forming cross-linked chemical compositions useful in a wide variety of applications. Typically, such methods have consisted of the intermixing of selected components, one normally including a blowing agent, to form a product of selected density. Such prior art methods have been carried out for example in urethane systems based either on polyether or polyester components and known isocyanates as well as in epoxy systems. Other prior art techniques have been employed where preliminary expansion or foaming of the product was carried out before the product was applied to an application zone. Such techniques have commonly been denoted by the term "froth foaming" and have been widely used in applications for depositing both rigid and flexible foams for a variety of end uses. However, these "froth foaming" techniques have generally been characterized by continued expansion of the material due to physical characteristics of a blowing agent contained therein or to reaction of the components for producing additional blowing agent to result in continued expansion.
In addition to compositions of the type referred to above, it has also been known in the prior art to employ coal tar products as cross-linking agents in order to achieve both economy and waterproofing in the resulting end product.
In yet other prior art applications, such materials have also been sprayed onto selected application zones including structural members and other surfaces, with foaming taking place after the material is sprayed, to result in a final product.
Even with all of these prior art techniques for combining cross-linking components to form different chemical compositions, there has been found to remain a need for improved apparatus and methods of carrying out such reactions in order to achieve improved characteristics in the resulting product. The manner in which the present invention achieves these improvements is made apparent in the following description.